CVE-2020-26507
📋 TL;DR
This CSV injection vulnerability in Marmind web application version 4.1.141.0 allows attackers to embed malicious formulas in exported CSV files. When victims open these files in spreadsheet software like Excel, the formulas can execute commands, potentially giving attackers remote access to their computers. All users of the vulnerable Marmind version who download and open CSV exports are affected.
💻 Affected Systems
- Marmind web application
📦 What is this software?
Marmind by Marmind
⚠️ Risk & Real-World Impact
Worst Case
Attacker gains remote code execution on victim's computer, leading to full system compromise, data theft, and lateral movement within the network.
Likely Case
Victim opens malicious CSV file in Excel, triggering command execution that could install malware, steal credentials, or establish backdoor access.
If Mitigated
With proper controls, CSV files are opened in safe viewers or sanitized before export, preventing formula execution.
🎯 Exploit Status
Exploitation requires authenticated access to inject formulas, but CSV injection techniques are well-documented and easy to implement.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version after 4.1.141.0
Vendor Advisory: https://www.marmind.com/en/
Restart Required: Yes
Instructions:
1. Contact Marmind support for patched version. 2. Backup configuration and data. 3. Apply update following vendor instructions. 4. Restart Marmind services. 5. Verify fix by testing CSV export functionality.
🔧 Temporary Workarounds
CSV Sanitization
allImplement server-side sanitization to prefix formula cells with apostrophe or strip dangerous characters from CSV exports.
Excel Safe Mode
windowsConfigure Excel to open CSV files in protected view or disable automatic formula execution.
🧯 If You Can't Patch
- Disable CSV export functionality in Marmind application
- Implement network segmentation to isolate Marmind servers and restrict user access to CSV downloads
🔍 How to Verify
Check if Vulnerable:
Test by entering formula payload (e.g., =cmd|' /C calc'!A0) in Notes or Description fields, export as CSV, and check if Excel executes it.Check Version:
Check Marmind web interface admin panel or configuration files for version number.Verify Fix Applied:
After patching, repeat vulnerability test with same payload; CSV should display formula as text without execution.📡 Detection & Monitoring
Log Indicators:
- Unusual CSV export requests
- Patterns of formula-like strings in user input fields
- Multiple failed export attempts
Network Indicators:
- Abnormal CSV download patterns from Marmind server
- Unexpected outbound connections after CSV file access
SIEM Query:
source="marmind_logs" AND (event="csv_export" AND (user_input CONTAINS "=" OR user_input CONTAINS "+" OR user_input CONTAINS "-" OR user_input CONTAINS "@"))